Basically, entanglent of individual qubits is an important component of quantum computation. Namely, two coupled qubits have more 'information' and behave differently than two isolated qubits.
Eg, a single qubit can be represented as a 2 element vector (spinor) with complex number elements. That is four Degrees of Freedom (DOF). However, the vector must be normalized, which eliminates one DOF, and the entire vector is phase invariant (can be multiplied by an arbitrary phase exp^(i gamma) for any phase gamma, without effect). So that really leaves two true DOF for a single qubit. These can be represented as angles on the Bloch sphere. See my other post on this thread for a link to my java app to visualize a qubit, and also show the relationship to the spinor vector.
However, a system of 2 qubits
can be represented as a 4 element complex vector. With the same constraints above for single qubits, this leaves 6 DOF for a two-qubit system. Each qubit individually has 2 DOF, but the entanglement itself represents another two DOF!
Many of the quantum computational processes you may have heard about (quantum teleportation, quantum communication, Shor's algorithm) invariably make use of his extra information in multi-qubit systems.
Eg, two spin-1/2 systems can couple together in the spin-0 singlet state, or as a spin-1 triplet state, or as a linear combination of both. This means that two fermions (subject to Pauli exclusion principle) can act like bosons when entangled, and do weird things in aggregate like Bose Einstein condensation. Very funky.